Manufacturing method for an ink jet recording head

ABSTRACT

This ink jet recording head manufacturing method comprises (A) forming a peeling layer  11  wherein peeling is induced by light irradiation, on a base plate  10  exhibiting light-transmissivity, (B) forming a common electrode film  3  on the peeling layer  11 , (C) forming a plurality of piezoelectric elements  4 , (D) forming a reservoir piece  5  comprising a lid structure that accommodates in its interior one or more piezoelectric elements  4 , which interior forms an ink reservoir  51 , (E) irradiating the peeling layer  11  with prescribed light from the base plate  10  side thereof, thereby producing peeling in the peeling layer  11 , and peeling the base plate  10  away, and (F) bonding a pressure chamber plate  2 , whereon are provided a plurality of pressure chambers  21 , to the common electrode film  3  separated from the base plate, so that the pressure chambers  21  are sealed.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates to improvements in ink jet recording heads. Moreparticularly, the present invention provides an ink jet recording headcapable of handling higher resolutions by providing a manufacturingmethod involving no deterioration in production yield even when usingpressure chamber plates that are thinner than conventionally.

2. Description of the Related Art

Ink jet recording heads according to the prior art comprise a pressurechamber plate, a nozzle plate bonded to one side of the pressure chamberplate, and a vibrating plate provided on the other side of the pressurechamber plate.

The pressure chamber plate is configured by forming multiple ink-holdingpressure chambers on a silicon wafer, and bonding thereto a nozzle platehaving nozzle holes arranged thereon corresponding to the pressurechambers (cavities). On the side of the vibrating plate opposite thepressure chambers are formed piezoelectric elements. Given thisconfiguration, when the pressure chambers are filled with ink and avoltage is applied to the piezoelectric elements, changes are producedin the volume of the piezoelectric material, and hence changes areproduced in the volumes of the pressure chambers. These changes inpressure cause ink to be discharged from the nozzle holes.

In the prior art, the thickness of the silicon wafer and the height ofthe pressure chambers are made roughly the same.

Demand has grown in recent years, however, for higher resolution in inkjet recording heads. In order to enhance the resolution of the ink jetrecording head, it is necessary to reduce both the width and height ofthe pressure chambers and the width of the partitioning side wallsbetween the pressure chambers.

However, the thickness of the silicon wafers that can be used currentlyis on the order of 200μ, which poses a limit on the height of the sidewalls partitioning the pressure chambers. When the thickness of thesilicon wafer is made thinner than this, the mechanical strength of thesilicon wafer cannot be preserved, leading to damage to the siliconwafer during the process of forming the pressure chambers and makinghandling otherwise problematic.

One conceivable solution is to form thinner pressure chamber platesseparately from the piezoelectric elements, use a different base platefor forming the piezoelectric elements, and finally bond the pressurechamber plate and the piezoelectric elements together. When this isdone, it is no longer necessary to send the pressure chamber platethrough multiple process steps in order to form the piezoelectricelements, and the drawbacks of employing a thin pressure chamber platecan be eliminated.

However, because the height of the piezoelectric elements is no morethan a few μ, it is very difficult to peel the piezoelectric elementsaway from the base plate after they are formed without affecting them.

SUMMARY OF THE INVENTION

In view of the problems noted in the foregoing, a first object of thepresent invention is to provide an ink jet recording head capable ofhandling higher resolution by employing a pressure chamber plate of thinthickness.

A second object of the present invention is to provide a manufacturingmethod for ink jet recording heads wherewith, by forming a pressurechamber plate of thin thickness in a separate process from thepiezoelectric elements, production yield is enhanced and costs arereduced.

A third object of the present invention is to provide a manufacturingmethod for ink jet recording heads wherewith, by unproblematicallypeeling away, from the base plate, the piezoelectric elements formed ina separate process from the pressure chamber plate, whereby productionyield is enhanced and costs are reduced.

An invention for achieving the first object noted above is an ink jetrecording head configured so that ink can be discharged by applying avoltage to piezoelectric elements, comprising: (a) a pressure chamberplate whereon are formed pressure chambers having nozzles that candischarge ink, such that the nozzles open in the same direction, (b) acommon electrode film formed so as to seal the pressure chambers on asurface of the pressure chamber plate different from the surface whereonthe nozzles are provided, (c) piezoelectric elements comprisingpiezoelectric thin films and upper electrodes, formed severally inpositions corresponding to the pressure chambers on the common electrodefilm, and (d) a reservoir piece provided with a lid-shaped structurethat accommodates in the interior thereof one or more piezoelectricelements, the interior whereof forms a reservoir.

The ink jet recording head according to the present invention isconfigured such that the nozzles and the pressure chambers are formedintegrally by the same component or components.

An invention for achieving the second and third objects noted above is amanufacturing method for an ink jet recording head configured such thatink can be discharged from nozzles provided in pressure chambers byapplying a voltage to piezoelectric elements and changing the volumethereof, comprising: (a) a peeling layer formation process for forming apeeling layer for producing peeling by the irradiation of light onto abase plate exhibiting light-transmissivity, (b) a common electrode layerformation process for forming a common electrode film on the peelingfilm, (c) a piezoelectric element formation process for forming aplurality of piezoelectric elements on the common electrode film, (d) areservoir formation process for forming a reservoir piece provided witha lid-shaped structure that accommodates in the interior thereof one ormore piezoelectric elements, the interior whereof forms a reservoir, (e)a peeling process for causing peeling in the peeling layer byirradiating the peeling layer from the base plate side with prescribedlight, thereby peeling away the base plate, and (f) a bonding processfor bonding the pressure chamber plate provided with the plurality ofpressure chambers onto the common electrode film from which the baseplate has been peeled, so as to seal the pressure chambers.

An invention for achieving the second and third objects noted above is amanufacturing method for an ink jet recording head configured such thatink can be discharged from nozzles provided in pressure chambers byapplying a voltage to piezoelectric elements and changing the volumethereof, comprising: (a) a peeling layer formation process for forming apeeling layer for producing peeling by the irradiation of light onto afirst base plate exhibiting light-transmissivity, (b) a common electrodelayer formation process for forming a common electrode film on thepeeling film, (c) a piezoelectric element formation process for forminga plurality of piezoelectric elements on the common electrode film, (d)an adhesive joining process for adhesively joining a second base plate,through an adhesive layer, to the surface whereon the piezoelectricelements are formed, (e) a first peeling process for causing peeling inthe peeling layer by irradiating the peeling layer from the first baseplate side with prescribed light, thereby peeling away the first baseplate, (f) a bonding process for bonding the pressure chamber plateprovided with the plurality of pressure chambers onto the commonelectrode film from which the first base plate has been peeled, so as toseal the pressure chambers, and (g) a second peeling process for peelingaway a second base plate.

The present invention also comprises an intermediate layer formationprocess for forming an intermediate layer between the peeling layer andthe common electrode film.

Based on the present invention, the piezoelectric element formationprocess comprises a process for laminating a piezoelectric layer ontothe common electrode film, a process for forming an upper electrode filmon the piezoelectric layer, and a process for forming piezoelectricelements by etching the laminated piezoelectric layer and upperelectrode layer.

Based on the present invention, the peeling layer may be formed using amaterial that is either amorphous silicon, an oxide ceramic, a nitrideceramic, an organic polymer, or a metal.

Based on the present invention, the pressure chamber plate is fabricatedby a process for forming a resin layer in a die, a process for peelingthe resin layer away from the die, and a process for making holes in theresin layer corresponding to the nozzles.

Based on the present invention, the second peeling process causespeeling to occur at the interfaces between the adhesive layer, and thepiezoelectric elements and the common electrode film.

Based on the present invention, the second peeling process causespeeling to occur in the adhesive layer.

Based on the present invention, the adhesive layer is configured so thatit contains a substance that can be hardened by the application ofenergy.

Based on the present invention, the adhesive layer is made up of athermoplastic resin.

Based on the present invention, an intermediate layer formation processis also comprised for forming an intermediate layer between the adhesivelayer and the second base plate.

Based on the present invention, the intermediate layer is configured soas to contain one or more metals selected from among Ni, Cr, Ti, Al, Cu,Ag, Au, and Pt, and causes peeling to occur at the interface between theintermediate layer and the adhesive layer.

Based on the present invention, the intermediate layer is made either ofporous silicon or an anodic oxide film, and, during the second peelingprocess, causes peeling to occur either in that intermediate layer orbetween that intermediate layer and the second base plate.

Based on the present invention, the intermediate layer is formed using amaterial that is either amorphous silicon, an oxide ceramic, a nitrideceramic, an organic polymer, or a metal, and, in the second peelingprocess, causes peeling to occur in the intermediate layer byirradiating that intermediate layer, from the second base plate side,with prescribed light.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a diagonal view of an ink jet printer of the presentinvention;

FIG. 2 is a diagonal view of the main components in an ink jet recordinghead of the present invention, showing a partial cross section thereof;

FIG. 3 is a set of cross-sectional views of the fabrication process foran ink jet recording head in a first embodiment, wherein FIG. 3Arepresents a peeling layer formation process, FIG. 3B a common electrodefilm formation process, FIG. 3C a piezoelectric element formationprocess, and FIG. 3D an etching process;

FIG. 4 is a set of cross-sectional views of the fabrication process forthe ink jet recording head in the first embodiment, wherein FIG. 4Erepresents a reservoir formation process, FIG. 4F a peeling process, andFIG. 4G a bonding process, while FIG. 4G provides a completecross-sectional view;

FIG. 5 is a set of cross-sectional views of the fabrication process forthe pressure chamber plate, wherein FIG. 5A represents a master platefabrication process, FIG. 5B a base plate formation process, FIG. 5C apeeling process, and FIG. 5D a nozzle formation process;

FIG. 6 is a set of cross-sectional views of the fabrication process foran ink jet recording head in a second embodiment, wherein FIG. 6Arepresents a piezoelectric element formation process, FIG. 6B an etchingprocess, FIG. 6C an adhesive process, and FIG. 6D a first peelingprocess;

FIG. 7 is a set of cross-sectional views of the fabrication process forthe ink jet recording head in the second embodiment, wherein FIG. 7Erepresents a bonding process, FIG. 7F a second peeling process, FIG. 7Ga washing process, and FIG. 7H a reservoir formation process;

FIG. 8 is a diagram of a modification of the second peeling process;

FIG. 9 is a pair of cross-sectional views of the fabrication process foran ink jet recording head in a third embodiment, wherein FIG. 9Arepresents an intermediate layer formation process and adhesion processand FIG. 9B represents a second peeling process.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

Preferred embodiments of the present invention will now be describedwith reference to the drawings.

First Embodiment

A first embodiment pertains to a manufacturing method for an ink jetrecording head wherein piezoelectric elements are formed on a baseplate, a reservoir piece is formed on that, and the piezoelectricelements are peeled away from the base plate and bonded to an integratedpressure chamber plate fabricated separately.

(Configuration of Ink Jet Recording Head)

In FIG. 1 is given a diagonal view of an ink jet printer containing anink jet recording head fabricated by the manufacturing method of thisembodiment. As depicted in FIG. 1, the ink jet printer 100 of thisembodiment comprises an ink jet recording head 101 of the presentinvention and a tray 103 in a main unit 102. Paper 105 is placed in thetray 103. When print data are supplied from a computer (not shown),internal rollers (not shown) feed the paper 105 into the main unit 102.The ink jet recording head 101 is driven in the directions indicated bythe double-headed arrow in FIG. 1 when the paper 105 passes next to therollers, and printing is performed. After printing, the paper 105 isdischarged from a discharge slot 104.

In FIG. 2 is-given a diagonal view of the main components of the ink jetrecording head noted above. A partial cross-sectional view is given hereto facilitate comprehension. A general description of the structure isgiven here; the detailed manufacturing method will be described later.In terms of the main components of the ink jet recording head, asdiagrammed in FIG. 2, a common electrode film 3 on which are formedpiezoelectric elements 4 is bonded to an integrally formed pressurechamber plate 2. In FIG. 2, a reservoir piece 5 (cf. FIG. 3) is formedso as to cover the common electrode film.

In the pressure chamber plate 2 are formed a plurality of cavities 21,each of which functions as a pressure chamber. This formation isaccomplished by etching a silicon monocrystalline substrate or the like.The cavities 21 are separated by side walls 22 formed therebetween. Eachof the cavities 21 is connected to a common flow path 23 by a supplyport 24. On one of the surfaces partitioning the cavities 21 areprovided nozzles 25. A common electrode film 3 is formed of a materialsuch as platinum and piezoelectric elements 4 are formed at positions onthe common electrode film 3 corresponding to the cavities 21. An inktank 33 is provided in the part of the common electrode film 3 thatcoincides with the common flow path 23.

The piezoelectric elements 4 are configured by laminating an upperelectrode onto a thin piezoelectric film formed by PZT, for example.

The upper electrode of each piezoelectric element 4 is connected to theoutput terminal of a drive circuit (not shown), and the common electrodefilm 3 is connected to the ground terminal of the drive circuit.

In the configuration of the ink jet recording head described above, whenthe drive circuit is driven and a prescribed voltage is applied to thepiezoelectric elements 4, volumetric changes are produced in thepiezoelectric elements 4, whereupon the pressure on the ink in thecavities 21 rises. When the pressure on the ink rises, ink drops aredischarged from the nozzles 25.

(Ink Jet Recording Head Manufacturing Method)

The ink jet recording head manufacturing method according to the presentinvention is described with reference to FIG. 3-5. These figures arecross-sectional diagrams of ink jet recording head fabrication processesshowing sections cut in the cavity width dimension.

Peeling Layer Formation Process (FIG. 3A):

In the peeling layer formation process, a peeling layer 11 for peelingaway the piezoelectric elements and the common electrode film is formedon a first base plate 10 which is a temporary base plate for formingpiezoelectric elements.

(First Base Plate)

The first base plate 10 may be anything that exhibitslight-transmissivity capable of transmitting irradiated light and thatalso exhibits resistance to heat and corrosion so as to be usable in thepiezoelectric element formation process. It is desirable that theirradiated light transmissivity be 10% or greater and preferably 50% orgreater. If the transmissivity is too low, attenuation of the irradiatedlight will be too large and a greater amount of energy will be requiredto peel away the peeling layer.

As to heat resistance, the formation processes generate temperaturesranging from 400° C. to 900° C., for example, wherefore the materialmust exhibit properties capable of withstanding these temperatures. Ifthe base plate exhibits outstanding heat resistance, then thetemperature can be set freely according to the conditions forpiezoelectric element formation.

If we take Tmax as the maximum temperature during the formation of thepiezoelectric elements constituting the transfer layer, it is desirablethat the base plate be made of a material having a distortion point thatexceeds Tmax. More specifically, it is desirable that this distortionpoint be 350° C. or higher, and preferably 500° C. or higher. Suchsubstances include such heat-resistance glasses as, for example, quartzglass, soda glass, Corning 7059 glass, and NEC OA-2 glass. Quartz glassis especially desirable because of its outstanding heat resistance.Whereas ordinary glass has a distortion point in the range of 400° C. to600° C., quartz glass has a distortion point of 1000° C.

There are no serious limiting factors on the thickness of the baseplate, but it should be between 0.1 mm and 0.5 mm, and preferablybetween 0.5 mm and 1.5 mm. If the substrate thickness is too thin,strength will be compromised, whereas, conversely, if it is too thick,attenuation will be induced in the irradiated light in cases where thebase plate transmissivity is low. In cases where the base plateirradiated-light transmissivity is high, however, the thickness may bemade thicker than the upper limit noted.

In order to have the irradiated light reach the peeling layer uniformly,the thickness of the base plate should be uniform.

(Peeling Layer)

The peeling layer 11 is a layer provided for producing peeling insidethe layer or at the interface thereof (called “intra-layer peeling” and“interfacial peeling,” respectively) when irradiated with light such asa laser beam. In other words, in the peeling layer, when light of acertain intensity is irradiated, the inter-molecular or inter-atomicbonding strength is lost or declines in the molecules or atoms making upthe constituent material, resulting in ablation and causing peeling tooccur. There are also cases where the irradiated light causes a gas tobe released from the peeling layer which leads to peeling. In some ofthese cases a component contained in the peeling layer becomes a gaswhich is released to induce peeling, while in other cases the peelinglayer absorbs the light, is gasified, and the resulting vapor isreleased to induce peeling.

The following compositions are conceivable for such a peeling layer.

1) Amorphous Silicon (a-Si)

This amorphous silicon may contain H (hydrogen). The hydrogen contentshould be 2 at % or greater, and preferably between 2 and 20 at %. Whenhydrogen is so contained, hydrogen is released by the light irradiation,generating internal pressure in the peeling layer and promoting peeling.The amount of this hydrogen content is adjusted according to the filmforming conditions. When the CVD method is used, for example, theadjustment is made by suitably setting such conditions as gascomposition, gas pressure, gas atmosphere, gas flow volume, gastemperature, substrate temperature, and the power of the lightintroduced.

2) Silicon oxide or silicate, titanium oxide or titanate, zirconiumoxide or zirconate, lanthanum oxide or lanthanate, various oxideceramics, dielectric substance, or semiconductor

Examples of silicon oxides include SiO, SiO₂, and Si₃O₂. Examples ofsilicates include K₂Si₃, Li₂SiO₃, CaSi0 ₃, ZrSiO₄, and Na₂SO.

Examples of titanium oxides include TiO, Ti₂O₃, and TiO₂. Examples oftitanates include, for example, BaTiO₄, BaTiO₃, Ba₂Ti₉O₂₀, BaTi₅O₁₁,CaTiO₃, SrTiO₃, PbTi₃, MgTiO₃, ZrTi₂, SnTiO₄, Al₂Ti₅, and TeTiO₃.

An example of a zirconium oxide is ZrO₂. Zirconates include, forexample, BaZrO₃, ZrSiO₄, PbZrO₃, MgZro₃, and K₂ZrO₃.

3) Nitride Ceramics Such as Silicon Nitride, Aluminum Nitride, andTitanium Nitride

4) Organic Polymer Materials

The organic polymer materials may be of any composition containing bondssuch as —CH₂—, —CO— (ketone), —CONH—(amide), NH— (imide), —COO— (ester),—N═N— (azo), and —CH═N— (cif) (these being inter-atomic bonds that aresevered by light irradiation), especially if such bonds are contained inabundance.

The organic polymer material may contain an aromatic lo hydrocarbon(either one or two or more benzene rings or condensed rings thereof).Specific examples of such organic polymers as these include polyolefinslike polyethylenes and polypropylenes, polyimides, polyamides,polyesters, polymethyl methacrylate (PMMA), polyphenylene sulfide (PPS),polyether sulfone (PES), and epoxy resins.

5) Metals

Examples of metals include Al, Li, Ti, Mn, In, Sn, Y, La, Ce, Nd Pr, Gd,and Sm, as well as alloys containing at least one of these metals.

(Peeling Layer Thickness)

The thickness of the peeling layer should normally be from 1 nm to 20μ,but preferably between 10 nm and 2μ, and the range of 40 nm to 1μ iseven more desirable. If the peeling layer thickness is too thin,thickness uniformity in the formed film will be lost, giving rise touneven peeling. If it is too thick, the power (light intensity) of theirradiated light necessary for peeling becomes large, and more time isrequired to remove remnants of the peeling layer left over afterpeeling.

(Formation Method)

The method for forming the peeling layer may be any method capable offorming a peeling layer of uniform thickness, and so may be selected atwill according to such conditions as peeling layer composition andthickness. Applicable methods include CVD (including MOCVD, low-pressureCVD, and ECR-CVD), vapor deposition, molecular beam vapor disposition(MB), sputtering, ion plating, PVD and other vapor phase film formationmethods, electroplating, immersion plating, non-electrolytic plating andother plating methods, Langmuir blow-jet (LB), spin coating, spraycoating, roller coating and other coating methods, any of variousprinting methods, transfer methods, ink jet methods, and powder jetmethods, etc.

In cases where the peeling layer is amorphous silicon (a-Si), it ispreferable to use CVD, and particularly low-pressure CVD or plasma CVD.In cases where the peeling layer film is formed using a ceramic materialand the sol-gel method, and in cases where an organic polymer materialis used, it is preferable that a coating method be used, andparticularly a spin coating method.

(Intermediate Layer)

Although not depicted in the drawings, it is desirable that anintermediate layer be formed between the peeling layer 11 and the commonelectrode film 3. This intermediate layer performs at least onefunction, whether as a protective layer for physically or chemicallyprotecting the layer being transferred during fabrication or use,insulating layer, barrier layer for blocking the migration of acomponent either to or from a layer being transferred, or reflectinglayer.

The composition of the intermediate layer can be appropriately selectedaccording to the purpose thereof. In the case of an intermediate layerformed between a transfer layer and a peeling layer made of amorphoussilicon, for example, a silicon oxide such as SiO₂ may be used. Otherintermediate layer compositions may contain Pt, Au, W, Ta, Mo, Al, Cr,or Ti, or an alloy containing such as the main component.

The thickness of the intermediate layer may also be suitably selectedaccording to the purpose of its formation. Ordinarily, a thickness of 10nm to 5 μ is desirable, with a range of 40 nm to 1 μ being even morepreferable.

The method of forming the intermediate layer may be any of the methodsnoted above for the peeling layer. The intermediate layer may be made asa single layer, or, alternatively, it may be made in two or more layershaving either the same composition or one using a plurality ofmaterials.

Common Electrode Film Formation Process (cf. FIG. 3B):

The common electrode film formation process is a process wherein thecommon electrode film 3 is formed on the peeling layer 11. The commonelectrode film functions as one electrode for the piezoelectricelements.

There is no particular limitation on the composition of the commonelectrode film 3 so long as the conductivity is high and it canwithstand the temperatures encountered during piezoelectric elementformation. Such metals as Pt, Au, Al, Ni, and In may be used.

For the method of forming the common electrode film 3, any methodsuitable to the composition and thickness thereof may be selected. Thismay be a sputtering method, vapor deposition method, CVD method,electroplating method, or non-electrolytic plating method, etc.

Piezoelectric Element Formation Process (cf. FIG. 3C):

The piezoelectric element formation process is a process for forming thepiezoelectric thin film 41 and the upper electrode film 42 on the commonelectrode film 3 in the prescribed thicknesses.

For the composition of the piezoelectric thin film 41, the ferroelectricceramics typified by lead zirconate titanate (PZT) are ideal.

The formation of the piezoelectric thin film should be by a sol-gelprocess. This sol-gel process is implemented by repeating a procedure,wherein a PZT-based sol made in the requisite composition is coated ontothe common electrode film 3 and this is sintered, a prescribed number oftimes. The coating method used may be spin coating, roller coating, ordie coating, etc. After repeating the prescribed number of coatings andsinterings, the whole is subjected to a final baking, whereupon apiezoelectric thin film 41 having a perovskite crystalline structure isformed. A sputtering process may be used as well as the sol-gel process.

The composition and forming method for the upper electrode film 42 arethe same as for the common electrode film 3.

Etching Process (FIG. 3D):

In the etching process, the upper electrode film and the piezoelectricthin film are etched to form the piezoelectric elements.

Dry etching, which exhibits outstanding anisotropy, should be used asthe etching method. This etching is performed after placing a resistpatterned in the shape of the piezoelectric elements on the upperelectrode film 42. The etching rate is adjusted by selecting suitableetching gases. Etching time is monitored, the areas of the upperelectrode film 42 and piezoelectric thin film 41 where no resist isprovided are removed, and the common electrode film 3 is exposed. Afteretching, the resist is removed by ashing it.

Reservoir Formation Process (FIG. 4E):

In the reservoir formation process, the reservoir piece is formed so asto cover the piezoelectric elements. The reservoir piece 5 is acomponent having a ⊃-shaped cross-section that forms a cap, asdiagrammed in FIG. 4E. In one part thereof is provided an opening (notshown) for supplying ink from an external ink tank.

The reservoir piece 5 need not be especially heat-resistant, but it doesneed to exhibit a certain mechanical strength and durability whenexposed to ink. Hence the composition of the reservoir piece may be ofany material selected from among resins, silicon, glass, or metal, etc.

Wiring for the piezoelectric elements is implemented prior to bondingthe reservoir piece 5 in place. That is, the output terminal of thedrive circuit (not shown) and the upper electrode 42 of each of thepiezoelectric elements 4 are connected, and the ground terminal of thedrive circuit and the common electrode film 3 are connected. Then thereservoir piece 5 is bonded in place so as to cover the piezoelectricelements 4. Inside the reservoir piece 5 is formed an ink reservoir 51.Any resin may be selected for bonding the reservoir piece 5.

Peeling Process (FIG. 4F):

In the peeling process, light 60 is irradiated from the back side(bottom side in FIG. 4F) of the first base plate 10. This causesablation to occur in the peeling layer 11, and the first base plate 10is peeled away.

The kind of peeling that occurs in the peeling layer due to theirradiation of light, that is, whether intra-layer peeling orinterfacial peeling, is determined by the peeling layer composition, theirradiated light, and other factors such as the type of irradiatedlight, wavelength, intensity, and depth of penetration.

The irradiated light may be any electromagnetic radiation, of whateverwavelength, that will cause intra-layer peeling and/or interfacialpeeling in the peeling layer, such as x-rays, UV radiation, visiblelight, infrared radiation (heat rays), laser beam, milliwaves, ormicrowaves. Electron beams or nuclear radiation (α rays, β rays, γ rays)may also be used. Among these, however, laser beams are preferredbecause they readily cause ablation in the peeling layer.

The laser apparatus for producing such laser beams may be any type ofgas laser or solid (i.e. semiconductor) laser. Excimer lasers, Nd-YAGlasers, argon lasers, CO₂ lasers, CO lasers, and He-Ne lasers areparticularly well suited to this purpose, with the excimer laser beingespecially preferred. The excimer laser outputs high energy in the shortwavelength region, and so is capable of producing ablation in thepeeling layer in an extremely short time. Thus very little temperaturerise is induced in adjacent or nearby layers, making it possible toachieve peeling while holding layer degradation and damage to a bareminimum.

When the peeling layer 11 exhibits an ablation-producing wavelengthdependence, the wavelength of the irradiated laser beam should bebetween 100 nm and 350 nm or so. In order to produce such layer changesas gas release, vaporization, or sublimation, the wavelength of thelaser beam should preferably be from 350 nm to 1200 nm or so.

The energy density of the irradiated laser beam should be in the rangeof 10 to 5000 mj/cm² when an excimer laser is used. The irradiation timeshould be 1 to 1000 nsec or so, and preferably within the range of 10 to100 nsec. If the energy density is too low or the irradiation time istoo short, adequate ablation is not produced. If the energy density istoo high or the irradiation time is too long, the transfer layer may beadversely affected by irradiated light passing through the peeling layeror intermediate layer.

The light should be irradiated so that the intensity thereof is uniform.The direction of irradiation is not limited to a direction perpendicularto the peeling layer; it may be inclined at a prescribed angle to thepeeling layer. In cases where the area of the peeling layer is largerthan the area which can be irradiated by one irradiation, theirradiation may be divided into a number of irradiations to cover theentire area of the peeling layer. Alternatively, the same place may beirradiated a number of times. It is also permissible that the same ordifferent areas be irradiated multiple times with light of differentkinds having different wavelengths (bands).

After peeling away the first base plate 10, if there are remnants of thepeeling layer on the common electrode film 3, these are removed bywashing.

Bonding Process (FIG. 4G):

The bonding process is a process for bonding, to the common electrodefilm 3, a separately fabricated pressure chamber plate 2. A simpledescription of the method of fabricating the pressure chamber plate isnow given, making reference to FIG. 5.

Master plate fabrication process (FIG. 5A): A master plate 16 is firstfabricated for transferring the pressure chamber plate 2. The masterplate 16 is fabricated by forming a pattern on the base material,corresponding to the cavities 21 and common flow path 23, and etching toa prescribed depth. The composition of the base material, i.e. of themaster plate, may be silicon, or some other substance such as glass,quartz, resin, metal, ceramic, or film, so long as it is etchable. Theresist for forming the pattern may be a positive resist comprising acresol-novolac resin into which a diazo-naphthoquinone derivative hasbeen mixed as the photosensitive agent. This is applied as is. Theresist layer is formed by spin coating, dipping, spray coating, rollercoating, or bar coating.

After the light exposure, a development process is performed underprescribed conditions, whereupon the resist in the exposed areas isselectively removed. When further etching is performed in thiscondition, the portions corresponding to the side walls 22 are etched,resulting in a die for fabricating the pressure chamber plate 2. Eitherwet etching or dry etching may be selected as the etching method. Thisselection is made in conjunction with such conditions as the basematerial properties, the cross-sectional shapes that are etched, and theetching rate, etc.

After etching, the resist is removed, whereupon the master plate 16 isdone.

The depth of the etching during the etching process is made equivalentto a height corresponding to the side walls 22, etc., formed on thepressure chamber plate. The height of the side walls is designed atapproximately 200μ for an ink jet recording head having a resolution of720 dpi.

Base Plate Formation Process (FIG. 5B): After the master plate 16 isformed, the substrate material 2 b is coated onto the surface thereofand hardened to form the pressure chamber plate 2. There is noparticular limitation on the composition of the substrate material solong as it satisfies the properties required in the ink jet pressurechamber plate in terms of mechanical strength and corrosion resistance,etc. It is nevertheless desirable that this be a material that ishardened using light, heat, or both light and heat. When such a materialused, a general purpose exposure apparatus, baking oven, or hot platecan be used in the interest of lower costs and space savings. Materialswhich may be used for this purpose include such synthetic resins asacrylic resins, epoxy resins, melamine resins, novolac resins, styreneresins, and polyimide resins, as well as silicon-based polymers such asa poly-silazane. If the substrate material contains a solvent component,the solvent is removed by heat treatment. Thermoplastic materials mayalso be used for the substrate material. One suitable material, forexample, is hydrate glass having a water content of from several toseveral tens of wt %.

The substrate material coating method used may be spin coating, dipping,spray coating, roller coating, or bar coating, etc.

Substrate Peeling Process (FIG. 5C):

Next the hardened substrate material 2 b, that is to say the pressurechamber plate 2, is peeled away from the master plate 16.

The peeling method used is one wherein the master plate 16 is secured,and the pressure chamber plate 2 is pulled away while being held bysuction. In cases where the bonding between the master plate and thepressure chamber plate is very strong, the concave shapes in the masterplate 16 should be formed beforehand with a taper. It is alsopermissible to irradiate the interface between the master plate and thepressure chamber plate with light prior to peeling to first lower oreliminate the bonding forces between the master plate and the pressurechamber plate. By so doing, the inter-atomic or inter-molecular bondingforces at the interface between the master plate and the pressurechamber plate are weakened or eliminated, thereby promoting theseparation by the gas released from the pressure chamber plate. Lightsuch as from an excimer laser should be used for this purpose. Whenlight is to be irradiated, it is necessary to form the master plate 16of a light-transmissive material. It is also preferable that a layercorresponding to the peeling layers described in the foregoing be formedat the interface between the master plate 16 and the pressure chamberplate 2. As to the specific method, those described in the foregoing maybe used as described.

Nozzle Formation Process (FIG. 5D):

Nozzles 25 are formed in the pressure chamber plate 2 after it has beenpeeled away.

There is no particular limitation on the method for forming the nozzles25. The various methods that can be applied include lithography, laserprocessing, FIB processing, and electrical discharge processing.

The pressure chamber plate 2 fabricated by the processes described aboveis bonded to the common electrode film 3 to which the reservoir piece 5has been bonded. The side of the pressure chamber plate 2 on which thenozzles are not formed is bonded to the common electrode film 3 so thatthe cavities 21 are matched with the respective piezoelectric elements4.

As based on the first embodiment described in the foregoing, thepiezoelectric elements are formed on a first base plate, a pressurechamber plate having a thin thickness is fabricated in a separateprocess, and the piezoelectric elements and pressure chamber plate arefinally bonded together, wherefore ink jet recording heads can bemanufactured with good production yield even when the pressure chamberplate is mechanically weak. Accordingly, the pressure chamber plate canbe made thinner than conventionally, making it possible to manufacturehigh-resolution ink jet recording heads.

Second Embodiment

A second embodiment pertains to a manufacturing method for an ink jetrecording head wherein piezoelectric elements formed on a base plate arefirst adhesively joined to another base plate, a pressure chamber plateis next bonded in place, and finally a reservoir piece is bonded inplace.

In this second embodiment, the structure of the ink jet recording headthat is fabricated is the same as in the first embodiment described inthe foregoing, and so is not further described here.

(Ink Jet Recording Head Manufacturing Method)

A manufacturing method for ink jet recording heads according to thepresent invention is now described with reference to FIG. 6 and 7. Thesefigures are cross-sectional diagrams of ink jet recording headfabrication processes showing sections cut in the cavity widthdimension.

Peeling Layer Formation Process, Common Electrode Film FormationProcess, Piezoelectric Element Formation Process (FIG. 6A), and EtchingProcess (FIG. 6B)

These processes are the same, respectively, as the peeling layerformation process (FIG. 3A), common electrode film formation process(FIG. 6B), piezoelectric element formation process (FIG. 6C), andetching process (FIG. 6D) in the first embodiment described earlier, andso are not further described here.

Adhesive Joining Process (FIG. 6C):

The adhesive joining process is a process for adhesively joining asecond base plate 12 to the surface of the first base plate 10 on whichthe piezoelectric elements 4 are formed, using an adhesive agent.

The composition of the second base plate 12 is the same as that of thefirst base plate 10 in the first embodiment described earlier, and isnot further described here.

The adhesive agent used for an adhesive layer 13, in terms ofcomposition, can be any adhesive agent whatsoever, such as an epoxy-,acrylate-, or silicone-based adhesive agent. These adhesive agents aredetermined according to whether, in a second peeling process, describedbelow, peeling is produced at the interface of the adhesive layer orinside the layer.

In this embodiment, however, it is necessary to produce intra-layerpeeling inside the adhesive layer by the application of light, heat, ora combination of both light and heat. For this reason, what is usedshould either be a thermoplastic resin, or something having a —CH₂—,—CO— ketone), —CONH— amide), —NH(imide), —COO— ester), —N=N—azo), or—CH═N— cif) bond (which inter-atomic bonds are severed by theirradiation of light). Or it may be something having in its constituentformula an aromatic hydrocarbon (either one or two or more benzene ringsor condensed rings thereof). Specific examples of such organic polymermaterials include such polyolefin resins as polyethylenes andpolypropylenes, polyimide resins, polyamide resins, polyester resins,acrylic resins, epoxy resins, melamine resins, and phenol resins, etc.

The adhesive layer 13 is formed by a coating method, for example. When ahardening adhesive agent is employed, the hardening adhesive agent iscoated onto the surface of the piezoelectric elements 4 that constitutethe transfer layer, to which is bonded the second base plate 12. Then,using a hardening method suitable to the properties of that hardeningadhesive agent, that hardening adhesive agent is hardened, and thetransfer layer and the second base plate 12 are adhesively joined.

When a photo-hardening adhesive agent is employed, the photo-hardeningadhesive agent should be coated onto the transfer layer, thelight-transmissive second base plate 12 placed on the unhardenedadhesive layer, and the hardening light then irradiated from the secondbase plate side to harden the adhesive agent.

The adhesive layer 13 may also be formed on the second base plate 12side and the transfer layer adhesively joined thereupon.

First Peeling Process (FIG. 6D) and Bonding Process (FIG. 7E):

The first peeling process and the bonding process are the same as thepeeling process (FIG. 4F) and the bonding process (FIG. 4G) in the firstembodiment, described earlier, and so are not further described here.The pressure chamber plate 2 fabrication is the same as in the firstembodiment also (FIG. 5).

Second Peeling Process (FIG. 7F):

The second peeling process is a process for producing intra-layerpeeling in the adhesive layer 13 and thereby peeling the second baseplate 12 away from the pressure chamber plate 2.

In this process, peeling is produced in the adhesive layer by subjectingthe adhesive layer 13 to prescribed energy. In cases where athermoplastic resin is employed in the adhesive layer, peeling isproduced by applying heat overall so that the transition temperature ofthe thermoplastic resin is exceeded.

Any adhesive agent left remaining about the periphery of thepiezoelectric elements 4 in the intra-layer peeling is removed by awashing process. A solvent is used to remove the adhesive agent whichwill not adversely affect either the piezoelectric elements or thecommon electrode film. Examples of solvents that can be used for thispurpose include acetone, isopropyl alcohol, ethylene glycol monoethylether acetate, propylene glycol monomethyl ether acetate, benzene,xylene, cresol, chlorobenzene, toluene, butyl acetate, normal hexane,cyclohexane, methyl ethyl ketone, dichloromethane,N,N-dimethylformamide, and dimethyl sulfoxide.

Reservoir Formation Process (FIG. 7H):

The reservoir piece formation process is a process for bonding in placethe reservoir piece 5 so that it covers the piezoelectric elements fromwhich the adhesive agent has been removed. The details of this are thesame as the reservoir formation process in the first embodimentdescribed earlier (FIG. 4E), and are not reiterated here.

With this embodiment, it is possible to produce peeling at theinterfaces between the adhesive layer 13, and the piezoelectric elements4 and common electrode film 3, by appropriately selecting the adhesiveagent composition and the peeling method. When, for example, an adhesiveagent is selected that exhibits greater bonding strength with the secondbase plate than the bonding strength with the piezoelectric elements 4and common electrode film 3, as diagrammed in FIG. 8, it is possible toproduce peeling from the interfaces between the adhesive layer 13, andthe piezoelectric elements 4 and the common electrode film 3. Anadvantage of producing peeling in this way is that the washing in thewashing process can be done easily.

As based on this second embodiment, as described in the foregoing, thepiezoelectric elements are formed on a first base plate, this is bondedto a second base plate, and the first base plate is peeled away. A thinpressure chamber plate is fabricated in a separate process, and thepiezoelectric elements and pressure chamber plate are finally bondedtogether, wherefore ink jet recording heads can be manufactured withgood production yield even when the pressure chamber plate ismechanically weak. Accordingly, the pressure chamber plate can be formedthinner than conventionally, wherefore it is possible to manufacturehigh-resolution ink jet recording heads.

As based on this second embodiment, in particular, the piezoelectricelements are fixed by an adhesive layer to a second base plate prior topeeling away the first base plate, wherefore the piezoelectric elementscan be handled easily and safely during the manufacturing process.

Third Embodiment

In a third embodiment of the present invention, the adhesive joiningprocess and second peeling process of the second embodiment aremodified. The ink jet recording head and the manufacturing methodtherefor are generally the same as in the embodiments described already.What is different, however, is that an intermediate layer 14 is providedprior to the adhesive joining process (FIG. 6C) described in theforegoing, after which the second base plate 12 is adhesively joined.

Modification of Adhesive Joining Process (FIG. 9A):

Before the adhesive joining process, the intermediate layer 14 is formedon the second base plate 12.

The composition of the intermediate layer 14 is a composition wherewithpeeling is readily produced at the interface with the adhesive layer 13,that is, a composition exhibiting low bonding strength with the adhesivelayer 13.

When an acrylate-based adhesive agent is used in the adhesive layer 13,for example, a composition may be utilized which contains one or moremetals selected from among Ni, Cr, Ti, Al, Cu, Ag, Au, and Pt. Thesemetals, in general, exhibit a low bonding strength with acrylate bondingagents, and permit well controlled film formation using a vacuum filmforming technique such as sputtering, vapor deposition, or CVD.

The composition used for the intermediate layer 14 may be a compositionwherewith peeling can be readily induced, either within the intermediatelayer 14, or at the interface between the intermediate layer 14 and thesecond base plate 12. This may be the same composition as for thepeeling layer 11 described already, or it may be porous silicon oralumina or some other anodic oxide film.

Modification of Second Peeling Process (FIG. 9B):

In order to peel the second base plate 12 away from the adhesive layer13 in cases where an intermediate layer 14 having the same compositionas the peeling layer 11 described in the foregoing is used, peeling isproduced by irradiating the intermediate layer 14 with light (laserbeam) from the second base plate 12 side, as diagrammed in FIG. 9B.

When porous silicon is used, it is possible, by cutting, to achievepeeling either inside the intermediate layer 14 or at the interfacebetween the intermediate layer 14 and the second base plate 12. When ananodic oxide film is employed, it is possible to produce peeling insidethe intermediate layer 14, by cutting, or mechanically, applying anelectrical field, and by cutting, for example, either inside theintermediate layer 14 or at the interface between the intermediate layer14 and the second base plate 12. The adhesive layer 13 left remaining onthe pressure chamber plate 2 may be removed by washing, using a solventtreatment or the like.

As based on this third embodiment, as described in the foregoing, anintermediate layer is provided, wherefore peeling can readily beproduced between the pressure chamber plate and the second base plate.

Industrial Utilization Possibilities

As based on the present invention, a thin pressure chamber plate iscomprised, wherefore ink jet recording heads can be provided which arecompatible with higher resolution.

As based on the manufacturing method for ink jet recording headsaccording to the present invention, a thin pressure chamber plate isformed in a separate process from the piezoelectric elements, whereforeproduction yield can be improved, and hence costs reduced.

As based on the manufacturing method for ink jet recording headsaccording to the present invention, a manufacturing method is providedwherewith piezoelectric elements formed in a separate process from thepressure chamber plate are peeled away from the base plateunproblematically, wherefore production yield can be improved, and hencecosts reduced.

What is claimed is:
 1. A manufacturing method for an ink jet recordinghead configured so that ink can be discharged from nozzles provided inpressure chambers by applying voltage to piezoelectric elements toinduce volumetric changes therein, comprising: a peeling layer formationprocess for forming a peeling layer for producing peeling by irradiationof light onto a light transmissive base plate; a common electrode layerformation process for forming a common electrode film on said peelingfilm; a piezoelectric element formation process for forming a pluralityof piezoelectric elements on said common electrode film; a reservoirformation process for forming a reservoir piece provided with alid-shaped structure that accommodates in the interior thereof one ormore of said piezoelectric elements, said interior forming a reservoir;a peeling process for causing peeling in said peeling layer byirradiating said peeling layer from a base plate side thereof withprescribed light, thereby removing said peeling layer and peeling saidbase plate away from said common electrode film. after the peelingprocess, performing a bonding process for bonding a pressure chamberplate provided with said plurality of pressure chambers onto said commonelectrode film from which said base plate has been peeled, so as to sealsaid pressure chambers.
 2. The manufacturing method for an ink jetrecording head according to claim 1, further comprising an intermediatelayer formation process for forming an intermediate layer between saidpeeling layer and said common electrode film.
 3. The manufacturingmethod for an ink jet recording head according to claim 1, wherein saidpiezoelectric element formation process comprises steps for laminating apiezoelectric layer onto said common electrode film, for forming anupper electrode layer on said piezoelectric layer, and for etching saidlaminated piezoelectric layer and upper electrode layer to form saidpiezoelectric elements.
 4. The manufacturing method for an ink jetrecording head according to claim 1, wherein said peeling layer isformed using a material that is amorphous silicon, a ceramic oxide, aceramic nitride, an organic polymer, or a metal.
 5. The manufacturingmethod for an ink jet recording head according to claim 1, wherein saidpressure chamber plate is fabricated by a process for forming a resinlayer in a die, a process for peeling said resin layer away from saiddie, and a process for making holes corresponding to nozzles in saidresin layer.
 6. A manufacturing method for an ink jet recording headconfigured so that ink can be discharged from nozzles provided inpressure chambers by applying voltage to piezoelectric elements toinduce volumetric changes therein, the manufacturing method comprising:a peeling layer formation process for forming a peeling layer forproducing peeling by irradiation of light onto a light transmissive baseplate; a common electrode layer formation process for forming a commonelectrode film on said peeling film; a piezoelectric element formationprocess for forming a plurality of piezoelectric elements on said commonelectrode film; a peeling process for causing peeling in said peelinglayer by irradiating said peeling layer from a base plate side thereofwith prescribed light, thereby removing said peeling layer and peelingsaid base plate away from said common electrode film. after the peelingprocess, performing a bonding process for bonding a pressure chamberplate provided with said plurality of pressure chambers onto said commonelectrode film from which said base plate has been peeled, so as to sealsaid pressure chambers.